From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 19 Apr 2007 08:55:12 +0000 (+0000)
Subject: More sophisticated error handling
X-Git-Tag: strings-1.0~21
X-Git-Url: http://git.tdb.fi/?p=libs%2Fcore.git;a=commitdiff_plain;h=d2118ac101602cfe2d62fb7deb6ef3fcb0fe137b

More sophisticated error handling
A couple of win32 fixes
---

diff --git a/source/ascii.cpp b/source/ascii.cpp
index 10eb794..43f7053 100644
--- a/source/ascii.cpp
+++ b/source/ascii.cpp
@@ -4,11 +4,14 @@ using namespace std;
 
 namespace Msp {
 
-void Ascii::Encoder::encode_char(wchar_t c)
+void Ascii::Encoder::encode_char(wchar_t c_)
 {
+	// Win32 has typedef unsigned short wchar_t
+	int c=c_;
 	if(c<0 || c>0x7F)
-		throw CodecError("Can't express character in ASCII");
-	append(c);
+		error("Can't express character in ASCII");
+	else
+		append(c);
 }
 
 
@@ -16,9 +19,13 @@ void Ascii::Decoder::decode_char(const string &str, string::const_iterator &i)
 {
 	if(i==str.end())
 		return;
-	if(*i&0x80)
-		throw CodecError("Invalid ASCII string (undefined character)");
-	append(*i++);
+	else if(*i&0x80)
+	{
+		error("Invalid ASCII string (undefined character)");
+		++i;
+	}
+	else
+		append(*i++);
 }
 
 } // namespace Msp
diff --git a/source/ascii.h b/source/ascii.h
index 9322a8b..de4013d 100644
--- a/source/ascii.h
+++ b/source/ascii.h
@@ -11,17 +11,21 @@ public:
 	class Encoder: public StringCodec::Encoder
 	{
 	public:
+		Encoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Encoder(em) { }
 		void encode_char(wchar_t);
+	private:
+		void append_replacement() { append(032); }
 	};
 
 	class Decoder: public StringCodec::Decoder
 	{
 	public:
+		Decoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Decoder(em) { }
 		void decode_char(const std::string &, std::string::const_iterator &);
 	};
 
-	Encoder *create_encoder() const { return new Encoder; }
-	Decoder *create_decoder() const { return new Decoder; }
+	Encoder *create_encoder(ErrorMode em=THROW_ON_ERROR) const { return new Encoder(em); }
+	Decoder *create_decoder(ErrorMode em=THROW_ON_ERROR) const { return new Decoder(em); }
 };
 
 } // namespace Msp
diff --git a/source/codec.cpp b/source/codec.cpp
index efc9814..38ef4ab 100644
--- a/source/codec.cpp
+++ b/source/codec.cpp
@@ -25,6 +25,7 @@ bool StringCodec::detect(const string &str) const
 	{
 		for(string::const_iterator i=str.begin(); i!=str.end(); )
 			dec->decode_char(str, i);
+		dec->sync();
 	}
 	catch(const CodecError &)
 	{
@@ -36,6 +37,26 @@ bool StringCodec::detect(const string &str) const
 	return result;
 }
 
+void StringCodec::Encoder::error(const string &msg)
+{
+	switch(err_mode_)
+	{
+	case IGNORE_ERRORS: break;
+	case REPLACE_ERRORS: append_replacement(); break;
+	default: throw CodecError(msg);
+	}
+}
+
+void StringCodec::Decoder::error(const string &msg)
+{
+	switch(err_mode_)
+	{
+	case IGNORE_ERRORS: break;
+	case REPLACE_ERRORS: append(0xFFFD); break;
+	default: throw CodecError(msg);
+	}
+}
+
 /**
 Creates a codec for the given encoding.  The caller is responsible for deleting
 the codec when it's no longer needed.
diff --git a/source/codec.h b/source/codec.h
index 5fb29db..7acd88f 100644
--- a/source/codec.h
+++ b/source/codec.h
@@ -28,6 +28,13 @@ with it.
 class StringCodec
 {
 public:
+	enum ErrorMode
+	{
+		THROW_ON_ERROR,
+		IGNORE_ERRORS,
+		REPLACE_ERRORS
+	};
+
 	/**
 	Base class for string encoder.  Each codec class should contain an Encoder
 	class derived from this.
@@ -71,11 +78,14 @@ public:
 
 		virtual ~Encoder() { }
 	protected:
-		Encoder() { }
+		Encoder(ErrorMode em=THROW_ON_ERROR): err_mode_(em) { }
 		void append(char c) { buffer_+=c; }
 		void append(const char *s, unsigned l) { buffer_.append(s, l); }
 		void append(const std::string &s) { buffer_+=s; }
+		void error(const std::string &);
+		virtual void append_replacement() { }
 	private:
+		ErrorMode err_mode_;
 		std::string buffer_;
 	};
 
@@ -92,30 +102,26 @@ public:
 
 		/**
 		Ensures that all input has been processed.  If this is not the case any
-		buffers are cleared and an exception is thrown,
+		buffers are cleared and an error is triggered.
 		*/
 		virtual void sync() { }
 
-		/**
-		Resets the decoder, clearing a possibly erroneus state.  Does not flush
-		the internal buffer.
-		*/
-		virtual void reset() { }
-
 		const std::wstring &get() const { return buffer_; }
 		unsigned size() const { return buffer_.size(); }
 		void flush() { buffer_.clear(); }
 		virtual ~Decoder() { }
 	protected:
-		Decoder() { }
+		Decoder(ErrorMode em): err_mode_(em) { }
 		void append(wchar_t c) { buffer_+=c; }
 		void append(const std::wstring &s) { buffer_+=s; }
+		void error(const std::string &);
 	private:
+		ErrorMode err_mode_;
 		std::wstring buffer_;
 	};
 
-	virtual Encoder *create_encoder() const =0;
-	virtual Decoder *create_decoder() const =0;
+	virtual Encoder *create_encoder(ErrorMode =THROW_ON_ERROR) const =0;
+	virtual Decoder *create_decoder(ErrorMode =THROW_ON_ERROR) const =0;
 	virtual bool    detect(const std::string &) const;
 	virtual ~StringCodec() { }
 protected:
diff --git a/source/iso2022jp.cpp b/source/iso2022jp.cpp
index ab31456..5a51a64 100644
--- a/source/iso2022jp.cpp
+++ b/source/iso2022jp.cpp
@@ -7,8 +7,11 @@ using namespace std;
 
 namespace Msp {
 
-void Iso2022Jp::Encoder::encode_char(wchar_t c)
+void Iso2022Jp::Encoder::encode_char(wchar_t c_)
 {
+	// Win32 has typedef unsigned short wchar_t
+	int c=c_;
+
 	if(c>=0 && c<=0x7F && c!=0x5C && c!=0x7E)
 	{
 		if(mode!=ASCII && mode!=JISX0201)
@@ -34,12 +37,15 @@ void Iso2022Jp::Encoder::encode_char(wchar_t c)
 	{
 		unsigned short jis=ucs_to_jisx0208(c);
 		if(!jis)
-			throw CodecError("Can't express character in ISO-2022-JP");
-		if(mode!=JISX0208)
-			switch_mode(JISX0208);
+			error("Can't express character in ISO-2022-JP");
+		else
+		{
+			if(mode!=JISX0208)
+				switch_mode(JISX0208);
 
-		char buf[2]={jis>>8, jis};
-		append(buf, 2);
+			char buf[2]={jis>>8, jis};
+			append(buf, 2);
+		}
 	}
 }
 
@@ -60,7 +66,15 @@ void Iso2022Jp::Encoder::switch_mode(Mode m)
 	}
 }
 
-Iso2022Jp::Decoder::Decoder():
+void Iso2022Jp::Encoder::append_replacement()
+{
+	if(mode!=ASCII)
+		switch_mode(ASCII);
+	append(032);
+}
+
+Iso2022Jp::Decoder::Decoder(ErrorMode em):
+	StringCodec::Decoder(em),
 	mode(ASCII),
 	dec(new Ascii::Decoder),
 	escape(0)
@@ -81,7 +95,7 @@ void Iso2022Jp::Decoder::decode_char(const string &str, string::const_iterator &
 				case 0x1B284A: switch_mode(JISX0201); break; // ESC ( J
 				case 0x1B2440:                               // ESC $ @
 				case 0x1B2442: switch_mode(JISX0208); break; // ESC $ B
-				default: throw CodecError("Invalid ISO-2022-JP escape sequence");
+				default: error("Invalid ISO-2022-JP escape sequence");
 				}
 				escape=0;
 			}
@@ -103,17 +117,21 @@ void Iso2022Jp::Decoder::decode_char(const string &str, string::const_iterator &
 void Iso2022Jp::Decoder::sync()
 {
 	if(escape)
-		throw CodecError("Sync in middle of ISO-2022-JP escape sequence");
+	{
+		error("Sync in middle of ISO-2022-JP escape sequence");
+		escape=0;
+	}
+	
 	if(mode!=ASCII)
-		throw CodecError("Sync while not in ASCII mode");
-	append(dec->get());
-	dec->flush();
-}
-
-void Iso2022Jp::Decoder::reset()
-{
-	switch_mode(ASCII);
-	escape=0;
+	{
+		error("Sync while not in ASCII mode");
+		switch_mode(ASCII);
+	}
+	else
+	{
+		append(dec->get());
+		dec->flush();
+	}
 }
 
 void Iso2022Jp::Decoder::switch_mode(Mode m)
diff --git a/source/iso2022jp.h b/source/iso2022jp.h
index 8ded0d8..82803b6 100644
--- a/source/iso2022jp.h
+++ b/source/iso2022jp.h
@@ -18,22 +18,22 @@ public:
 	class Encoder: public StringCodec::Encoder
 	{
 	public:
-		Encoder(): mode(ASCII) { }
+		Encoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Encoder(em), mode(ASCII) { }
 		void encode_char(wchar_t);
 		void sync();
 	private:
 		Mode mode;
 
 		void switch_mode(Mode);
+		void append_replacement();
 	};
 
 	class Decoder: public StringCodec::Decoder
 	{
 	public:
-		Decoder();
+		Decoder(ErrorMode =THROW_ON_ERROR);
 		void decode_char(const std::string &, std::string::const_iterator &);
 		void sync();
-		void reset();
 	private:
 		Mode mode;
 		StringCodec::Decoder *dec;
@@ -42,8 +42,8 @@ public:
 		void switch_mode(Mode);
 	};
 
-	Encoder *create_encoder() const { return new Encoder; }
-	Decoder *create_decoder() const { return new Decoder; }
+	Encoder *create_encoder(ErrorMode em=THROW_ON_ERROR) const { return new Encoder(em); }
+	Decoder *create_decoder(ErrorMode em=THROW_ON_ERROR) const { return new Decoder(em); }
 };
 
 } // namespace Msp
diff --git a/source/iso646fi.cpp b/source/iso646fi.cpp
index 45c29ff..171c0a0 100644
--- a/source/iso646fi.cpp
+++ b/source/iso646fi.cpp
@@ -4,8 +4,11 @@ using namespace std;
 
 namespace Msp {
 
-void Iso646Fi::Encoder::encode_char(wchar_t c)
+void Iso646Fi::Encoder::encode_char(wchar_t c_)
 {
+	// Win32 has typedef unsigned short wchar_t
+	int c=c_;
+
 	if((c>=0 && c<=0x5A) || c==0x5F || (c>=0x61 && c<=0x7A))
 		append(c);
 	else if(c==0xC4)
@@ -27,7 +30,7 @@ void Iso646Fi::Encoder::encode_char(wchar_t c)
 	else if(c==0xFC)
 		append(0x7E);
 	else
-		throw CodecError("Can't express character in ISO-646-FI");
+		error("Can't express character in ISO-646-FI");
 }
 
 void Iso646Fi::Decoder::decode_char(const string &str, string::const_iterator &i)
@@ -57,7 +60,7 @@ void Iso646Fi::Decoder::decode_char(const string &str, string::const_iterator &i
 	else if(c<=0x7F)
 		append(c);
 	else
-		throw CodecError("Invalid ISO-646-FI string (undefined character)");
+		error("Invalid ISO-646-FI string (undefined character)");
 }
 
 }
diff --git a/source/iso646fi.h b/source/iso646fi.h
index 885015a..1f0df91 100644
--- a/source/iso646fi.h
+++ b/source/iso646fi.h
@@ -11,17 +11,21 @@ public:
 	class Encoder: public StringCodec::Encoder
 	{
 	public:
+		Encoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Encoder(em) { }
 		void encode_char(wchar_t);
+	private:
+		void append_replacement() { append(032); }
 	};
 
 	class Decoder: public StringCodec::Decoder
 	{
 	public:
+		Decoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Decoder(em) { }
 		void decode_char(const std::string &, std::string::const_iterator &);
 	};
 
-	Encoder *create_encoder() const { return new Encoder; }
-	Decoder *create_decoder() const { return new Decoder; }
+	Encoder *create_encoder(ErrorMode em=THROW_ON_ERROR) const { return new Encoder(em); }
+	Decoder *create_decoder(ErrorMode em=THROW_ON_ERROR) const { return new Decoder(em); }
 };
 
 } // namespace Msp
diff --git a/source/jisx0201.cpp b/source/jisx0201.cpp
index 0a88047..65abff2 100644
--- a/source/jisx0201.cpp
+++ b/source/jisx0201.cpp
@@ -4,8 +4,10 @@ using namespace std;
 
 namespace Msp {
 
-void JisX0201::Encoder::encode_char(wchar_t c)
+void JisX0201::Encoder::encode_char(wchar_t c_)
 {
+	// Win32 has typedef unsigned short wchar_t
+	int c=c_;
 	if(c>=0 && c<=0x7F && c!=0x5C && c!=0x7E)
 		append(c);
 	else if(c==0xA5)
@@ -15,7 +17,7 @@ void JisX0201::Encoder::encode_char(wchar_t c)
 	else if(c>=0xFF61 && c<=0xFF9F)
 		append(c-0xFEC0);
 	else
-		throw CodecError("Can't express character in JIS X 0201");
+		error("Can't express character in JIS X 0201");
 }
 
 void JisX0201::Decoder::decode_char(const string &str, string::const_iterator &i)
@@ -33,7 +35,7 @@ void JisX0201::Decoder::decode_char(const string &str, string::const_iterator &i
 	else if(c>=0xA1 && c<=0xDF)
 		append(c+0xFEC0);
 	else
-		throw CodecError("Invalid JIS X 0201 string (undefined character)");
+		error("Invalid JIS X 0201 string (undefined character)");
 }
 
 } // namespace Msp
diff --git a/source/jisx0201.h b/source/jisx0201.h
index 976a945..bf513f7 100644
--- a/source/jisx0201.h
+++ b/source/jisx0201.h
@@ -11,17 +11,21 @@ public:
 	class Encoder: public StringCodec::Encoder
 	{
 	public:
+		Encoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Encoder(em) { }
 		void encode_char(wchar_t);
+	private:
+		void append_replacement() { append(032); }
 	};
 
 	class Decoder: public StringCodec::Decoder
 	{
 	public:
+		Decoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Decoder(em) { }
 		void decode_char(const std::string &, std::string::const_iterator &);
 	};
 
-	Encoder *create_encoder() const { return new Encoder; }
-	Decoder *create_decoder() const { return new Decoder; }
+	Encoder *create_encoder(ErrorMode em=THROW_ON_ERROR) const { return new Encoder(em); }
+	Decoder *create_decoder(ErrorMode em=THROW_ON_ERROR) const { return new Decoder(em); }
 };
 
 } // namespace Msp
diff --git a/source/jisx0208.cpp b/source/jisx0208.cpp
index 4d46f70..e24673b 100644
--- a/source/jisx0208.cpp
+++ b/source/jisx0208.cpp
@@ -9,10 +9,13 @@ namespace Msp {
 void JisX0208::Encoder::encode_char(wchar_t ucs)
 {
 	unsigned short jis=ucs_to_jisx0208(ucs);
-	if(!jis) throw CodecError("Can't express character in JIS X 0208");
-
-	char buf[2]={jis>>8, jis};
-	append(buf, 2);
+	if(jis)
+	{
+		char buf[2]={jis>>8, jis};
+		append(buf, 2);
+	}
+	else
+		error("Can't express character in JIS X 0208");
 }
 
 
@@ -30,21 +33,19 @@ void JisX0208::Decoder::decode_char(const string &str, string::const_iterator &i
 	wchar_t ucs=jisx0208_to_ucs(high<<8 | *i++);
 	high=0;
 
-	if(!ucs)
-		throw CodecError("Invalid JIS X 0208 string (undefined character)");
-
-	append(ucs);
+	if(ucs)
+		append(ucs);
+	else
+		error("Invalid JIS X 0208 string (undefined character)");
 }
 
 void JisX0208::Decoder::sync()
 {
 	if(high)
-		throw CodecError("Sync in middle of JIS X 0208 character");
-}
-
-void JisX0208::Decoder::reset()
-{
-	high=0;
+	{
+		error("Sync in middle of JIS X 0208 character");
+		high=0;
+	}
 }
 
 wchar_t jisx0208_to_ucs(unsigned short jis)
diff --git a/source/jisx0208.h b/source/jisx0208.h
index 16f8202..12dc2c0 100644
--- a/source/jisx0208.h
+++ b/source/jisx0208.h
@@ -11,12 +11,16 @@ public:
 	class Encoder: public StringCodec::Encoder
 	{
 	public:
+		Encoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Encoder(em) { }
 		void encode_char(wchar_t);
+	private:
+		void append_replacement() { append("!)"); }
 	};
 
 	class Decoder: public StringCodec::Decoder
 	{
 	public:
+		Decoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Decoder(em), high(0) { }
 		void decode_char(const std::string &, std::string::const_iterator &);
 		void sync();
 		void reset();
@@ -24,8 +28,8 @@ public:
 		char high;
 	};
 
-	Encoder *create_encoder() const { return new Encoder; }
-	Decoder *create_decoder() const { return new Decoder; }
+	Encoder *create_encoder(ErrorMode em=THROW_ON_ERROR) const { return new Encoder(em); }
+	Decoder *create_decoder(ErrorMode em=THROW_ON_ERROR) const { return new Decoder(em); }
 };
 
 extern wchar_t jisx0208_to_ucs(unsigned short);
diff --git a/source/latin1.cpp b/source/latin1.cpp
index fe9e1a4..319429f 100644
--- a/source/latin1.cpp
+++ b/source/latin1.cpp
@@ -4,11 +4,14 @@ using namespace std;
 
 namespace Msp {
 
-void Latin1::Encoder::encode_char(wchar_t c)
+void Latin1::Encoder::encode_char(wchar_t c_)
 {
+	// Win32 has typedef unsigned short wchar_t
+	int c=c_;
 	if(c<0 || c>0xFF)
-		throw CodecError("Can't express character in Latin-1");
-	append(c);
+		error("Can't express character in Latin-1");
+	else
+		append(c);
 }
 
 void Latin1::Decoder::decode_char(const string &str, string::const_iterator &i)
diff --git a/source/latin1.h b/source/latin1.h
index 20eb426..12d880c 100644
--- a/source/latin1.h
+++ b/source/latin1.h
@@ -11,17 +11,21 @@ public:
 	class Encoder: public StringCodec::Encoder
 	{
 	public:
+		Encoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Encoder(em) { }
 		void encode_char(wchar_t);
+	private:
+		void append_replacement() { append(032); }
 	};
 
 	class Decoder: public StringCodec::Decoder
 	{
 	public:
+		Decoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Decoder(em) { }
 		void decode_char(const std::string &, std::string::const_iterator &);
 	};
 
-	Encoder *create_encoder() const { return new Encoder; }
-	Decoder *create_decoder() const { return new Decoder; }
+	Encoder *create_encoder(ErrorMode em=THROW_ON_ERROR) const { return new Encoder(em); }
+	Decoder *create_decoder(ErrorMode em=THROW_ON_ERROR) const { return new Decoder(em); }
 };
 
 } // namespace Msp
diff --git a/source/utf8.cpp b/source/utf8.cpp
index f95ad9c..030406d 100644
--- a/source/utf8.cpp
+++ b/source/utf8.cpp
@@ -8,7 +8,10 @@ void Utf8::Encoder::encode_char(wchar_t c)
 {
 	unsigned code=c;
 	if(code>0x10FFFF)
-		throw CodecError("Can't express character in UTF-8");
+	{
+		error("Can't express character in UTF-8");
+		return;
+	}
 
 	unsigned bytes=1;
 	if(code>0xFFFF)
@@ -43,8 +46,11 @@ void Utf8::Decoder::decode_char(const string &str, string::const_iterator &i)
 		if(bytes==0)
 		{
 			if((*i&0xC0)==0x80)
-				throw CodecError("Invalid UTF-8 string (tail byte when expecting head)");
-
+			{
+				error("Invalid UTF-8 string (tail byte when expecting head)");
+				++i;
+				break;
+			}
 			else if(*i&0x80)
 			{
 				unsigned mask=0x40;
@@ -52,11 +58,20 @@ void Utf8::Decoder::decode_char(const string &str, string::const_iterator &i)
 					++bytes;
 
 				if(bytes>3)
-					throw CodecError("Invalid UTF-8 string (overlong multibyte sequence)");
-
-				code=(*i++)&(mask-1);
-				if(!code)
-					throw CodecError("Invalid UTF-8 string (denormalized multibyte sequence)");
+				{
+					error("Invalid UTF-8 string (overlong multibyte sequence)");
+					++i;
+					break;
+				}
+				else
+				{
+					code=(*i++)&(mask-1);
+					if(!code)
+					{
+						error("Invalid UTF-8 string (denormalized multibyte sequence)");
+						break;
+					}
+				}
 			}
 			else
 			{
@@ -67,7 +82,11 @@ void Utf8::Decoder::decode_char(const string &str, string::const_iterator &i)
 		else
 		{
 			if((*i&0xC0)!=0x80)
-				throw CodecError("Invalid UTF-8 string (head byte when expecting tail)");
+			{
+				error("Invalid UTF-8 string (head byte when expecting tail)");
+				++i;
+				break;
+			}
 
 			code=code<<6 | (*i++)&0x3F;
 			--bytes;
@@ -75,8 +94,9 @@ void Utf8::Decoder::decode_char(const string &str, string::const_iterator &i)
 			if(!bytes)
 			{
 				if(code>0x10FFFF)
-					throw CodecError("Invalid UTF-8 string (character out of range)");
-				append(code);
+					error("Invalid UTF-8 string (character out of range)");
+				else
+					append(code);
 				break;
 			}
 		}
@@ -86,7 +106,10 @@ void Utf8::Decoder::decode_char(const string &str, string::const_iterator &i)
 void Utf8::Decoder::sync()
 {
 	if(bytes)
-		throw CodecError("Sync in the middle of multibyte UTF-8 sequence");
+	{
+		error("Sync in the middle of multibyte UTF-8 sequence");
+		bytes=0;
+	}
 }
 
 void Utf8::Decoder::reset()
diff --git a/source/utf8.h b/source/utf8.h
index 0475523..40b4fb8 100644
--- a/source/utf8.h
+++ b/source/utf8.h
@@ -11,13 +11,16 @@ public:
 	class Encoder: public StringCodec::Encoder
 	{
 	public:
+		Encoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Encoder(em) { }
 		void encode_char(wchar_t);
+	private:
+		void append_replacement() { append("\357\277\275"); }
 	};
 
 	class Decoder: public StringCodec::Decoder
 	{
 	public:
-		Decoder(): bytes(0), code(0) { }
+		Decoder(ErrorMode em=THROW_ON_ERROR): StringCodec::Decoder(em), bytes(0), code(0) { }
 		void     decode_char(const std::string &, std::string::const_iterator &);
 		void     sync();
 		void     reset();
@@ -26,8 +29,8 @@ public:
 		unsigned code;
 	};
 
-	Encoder *create_encoder() const { return new Encoder; }
-	Decoder *create_decoder() const { return new Decoder; }
+	Encoder *create_encoder(ErrorMode em=THROW_ON_ERROR) const { return new Encoder(em); }
+	Decoder *create_decoder(ErrorMode em=THROW_ON_ERROR) const { return new Decoder(em); }
 };
 
 } // namespace Msp